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One 23-year-old body builder who has been using steroids for five years remembers the immediate effects on his body. “You can feel yourself in the gym pushing 30, 40, 50 pounds heavier weight — my muscles were expanding and growing,” says "John," who didn't want to give his real name. “You can see veins popping out.”

Dr. Robert Dimeff of the Cleveland Clinic says athletes use steroids because the drugs are so effective. “You’ll get more strength," he says. "You’ll get more power.”

Steroids, says Dimeff, “definitely” work.

Steroid drugs are chemical cousins of the male hormone testosterone. Athletes use them to get the so-called anabolic effects that occur in a boy during puberty — the building of muscle, bone, and nerve and blood tissue, but without the hair growth, voice changes and sexual effects.

Psychological effectsThe drugs can cause psychological problems, especially aggression. “And then when they stop, and they don’t realize — they can’t figure out how they were so destructive and mean,” says Dimeff.

Physical effects like acne and high blood pressure usually go away when athletes stop using the drugs.

So why are steroids outlawed? “Clearly, the side effects have a role,” adds Dimeff. “But the cheating is a thing that goes against all the philosophy of sport.”

New drugs harder to detectBut the big money in sports can easily trump ideals. A case in point is the “designer steroid” THG, which was developed to slip by drug testing. It was so good that the head of the United States' largest drug-testing lab had never heard of it until someone sent it to him anonymously.

“Somebody deliberately sat down and synthesized THG,” says Dr. Don Catlin of UCLA’s Olympic Drug Testing Lab. “And they designed it so that our routine test would not be able to detect it.”

Experts agree that only widespread testing — with constant vigilance for the ongoing cat-and-mouse schemes to beat the test — can possibly stop illegal steroid use.